EYE-OPENING: John Liu spends time with a neighbor-for-a-night (above), and Anthony Weiner, Rev. Al Sharpton and Christine Quinn (inset) sit with a resident in East Harlem. (
)

Living in public housing is a piece of cake — if you stay just one night and have a patrol of NYPD officers to watch your back.

Five mayoral candidates spent Saturday night at the Lincoln Houses in East Harlem under the watchful eyes of at least five times the normal number of uniformed cops, sources said — a fact that wasn’t lost on irked residents.

“It should be like this all the time, not because people are running for an election,” griped Diane Beebe, 61, a 15-year tenant who opened her New York City Housing Authority home to mayoral candidate Anthony Weiner for the night. “People should be able to sit outside their building and feel comfortable.”

According to law-enforcement sources, there were nearly 30 uniformed officers on duty overnight, as well as a deputy inspector.

On a normal night — when the candidates are in the comfort of their own posh pads — there are usually only five or six cops on patrol, sources and residents said.

“Even when we call them, they take their time getting here,” Beebe said. “I hope they’ll be able to keep it like it was last night, at a peaceful level — no gunplay, nobody screaming, hollering, shouting, pissing in the elevator, having sex in the stairway.”

An NYPD rep declined comment on the claims.

Patricia Herman, 60, who leads Lincoln’s residents association, said, “We want to see it like this on a daily basis, 24-7.”

Usually, “we don’t see them,’’ she said of the cops. “They don’t come out unless somebody gets killed.”

Neighbor Gladys Rosario said she was glad to see the police presence but added that she would like to see it more often, too.

“We were surrounded” by officers for the one night, said Rosario, who offered rice and beans to former Comptroller Bill Thompson, who was staying next door.

“There were police all over the place. It was very unusual for us. We’d like to see more, like we saw this morning. They shouldn’t just come out for the people running for mayor.”

Thompson joined four fellow candidates — City Council Speaker Christine Quinn, former Rep. Weiner, Public Advocate Bill de Blasio and Comptroller John Liu — in the sleepover.

They were there at the invitation of the Rev. Al Sharpton, who wanted to give the candidates a firsthand look at how the other half lives. Sharpton also slept over.

What the politicians got was an experience that was more eye-opening than any wake-up call from a high-end hotel.

“The apartment I stayed in had a bathroom that was covered with black mold,” Quinn said later.

“It was the worst I’ve ever seen. When the city of New York is the landlord, this is unacceptable.”

De Blasio, who stayed with his daughter, Chiara, 18, in one apartment, added, “What’s happening with NYCHA needs to be addressed. “Six-hundred-thousand New York residents are being treated like second-class citizens.”

De Blasio spent the night in shorts and a T-shirt on Katherine Wilson’s leather sofa and nearly missed the group’s early-morning news conference yesterday.

He and his daughter “were sleeping so well, I didn’t want to wake them up,” said Wilson, 57.

Wilson and her son, Reginald, 38, showed the candidate some mold on her wall and the shoddy paint job in her apartment.

“I just hope this is not the last time politicians do this, coming to these communities and seeing how people are doing and what they need,” Reginald said.

Thompson, who blasted NYCHA’s “poor maintenance record,” was a guest of Barbara Gamble, 67, and nearly hijacked the TV remote when a news story came on about him and his rival candidates at the complex.

“This morning I tried to make them some bacon and grits and sausage, but he said, ‘No, we’re running a little late. Not this morning.’ ”

At least one candidate for mayor, John Catsimatidis, 64, said he was unimpressed with the sleepover. He did not accept Sharpton’s challenge.

“I grew up on 135 St. in conditions like the #NYCHA Houses, unlike the other candidates who are out of touch & have no idea what it’s like,” he said in a message to his followers on Twitter.

Of course, the billionaire grew up in a different era, and much has changed in Harlem since then.

Sharpton spent part of his childhood in public housing, moving from middle-class Hollis, Queens, to a housing complex in Brownsville, Brooklyn, after his parents split up.

Quinn’s stay was quite rewarding for Lalla Diakite, 17, whose parents hosted the politician. When Lalla told Quinn about her trip to England next year, Quinn wrote her a check for $100 to help her cover expenses.